Brown dwarf

Among the thousands of different types of stellar objects that can be found in outer space, perhaps one of the strangest and most mysterious is the brown dwarf . This star, different from all the others, is a star that has not managed to begin the process of nuclear fusion of the material it has inside. In the same way, since they are not a star themselves, they are very easy to confuse with planets known as giants.

What is a brown dwarf?

A brown dwarf is a substellar object that does not have the ability to produce nuclear reactions , it is a type of star that does not have enough mass to produce its own brightness like a star does.


The brown dwarf is an astronomical object that is located in an intermediate place between a planet and a star . We can say that they are objects that are in space and that occupy a middle place between planets and stars because they do not have the necessary and sufficient amount to be able to shine like a normal star does. Despite this, they are even larger than some planets and glow in the infrared.


Brown dwarfs generally have a mass less than 0.075 that of the Sun, or about 75 times that of Jupiter . Many astronomers draw the line between brown dwarfs and planets at the lower melting boundary of about 13 Jupiter masses . They have the ability to produce energy through the fusion of deuterium , which is a rare isotope of hydrogen in its first millions of years. Brown dwarfs prevent further contraction because their nuclei are dense enough to withstand the degeneracy pressure of theelectrons .

Most brown dwarfs are red dwarfs that fail to trigger nuclear fusion . They have the ability to have planets around them, they emit light that is visible but faint, and they are cool enough to retain atmosphere just like a planet does . The surface temperatures depend on its mass and its age . Younger brown dwarfs have temperatures up to 2,800 K. All brown dwarfs eventually cool below stellar temperature of the minimum main sequence of around 1,800 K.


Brown dwarfs were first hypothesized in 1963 by the American astronomer Shiv Kumar , who first called them “black” dwarfs . The American astronomer Jill Tarter proposed the name “brown dwarf” in 1975 . Although brown dwarfs are not brown, the name was given because these objects were thought to have dust . Searches for brown dwarfs in the 1980s and 1990s found several results; but none were confirmed as a brown dwarf.

Astronomers at the University of California , Berkeley, observed lithium in an object in the Pleiades , which was later accepted as the first binary brown dwarf  Astronomers of the Observatory Palomar and Johns Hopkins University found a partner for a low – mass star called Gliese 229 B.

Composition of the brown dwarf

The brown dwarf is made up mainly of molecular hydrogen and it is also very cold because its temperature does not exceed 100 kelvin. When viewed on a telescope cloud it appears as a slick dark and opaque that can be seen in the light. These types of clouds are the raw material from which stars are formed.


Brown dwarfs are formed as a product that arises from failed stellar evolution . When a gas cloud collapses into itself, a protostar is created, which in other words is the embryo of a star. Many times, protostars manage to gain enough mass and an adequate temperature to trigger nuclear fusion of their material in the nucleus, becoming stars in the main sequence phase . In the case of brown dwarfs, they get stuckhalfway through and fail to acquire sufficient amounts of mass to cause hydrogen to begin to fuse into helium and to stabilize the temperature before it can become a star.


The possibility of habitability in planets that orbit a brown dwarf has been studied over the years, and it has been thought that the conditions for one of these stars to have a habitable planet are very strict because the habitable zone is very narrow and because the orbital eccentricity should be extremely low to prevent the creation of tidal forces that produce an uncontrolled greenhouse effect rendering them uninhabitable.

Brown dwarf in our solar system

A brown dwarf was discovered 98 light years away from the Sun. This discovery was made through a website where anyone can help find objects that are farther from the orbit of Neptune . The existence of the object has been confirmed by the Telescope Infrared of NASA in Hawaii and has been identified as a brown dwarf.

Bob Fletcher , a science teacher, was the first to spot the brown dwarf, when he observed a very faint object in several of the WISE telescope images and then the object was reported by volunteers from Russia, Serbia and the United States.

Featured brown dwarfs

Some of the brown dwarfs that have been identified are:

  • Teide 1 is indeed the first brown dwarf discovered
  • Gliesse 229 B
  • Calar Pleiades 3, or simply, Calar 3.
  • SDSS J0104 + 1535 is almost 90 times the mass of Jupiter.
  • AE Fornacis
  • Brown dwarf sub
  • WD 0137-349
  • COROT-3b


Some of the main curiosities of brown dwarfs are the following:

  • According to Dr. Brecher, the true color of brown dwarf stars is reddish orange and not brown as the name implies.
  • Brown dwarfs have more powerful auroras than any aurora ever detected in our solar system .
  • Y-type brown dwarfs are extremely cold , they could even be touched without being charred or burned, since their temperature is below 100 ° C.
  • The gravity that brown dwarfs possess would not allow us to get to be in them because we would be crushed to death instantly.

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